Table 1.

The properties of selected FPs and their use as probes for FRET microscopy. The peak excitation (Ex) and emission (Em) wavelengths, molar extinction coefficient (EC), quantum yield (QY), and relative brightness are listed.

Protein (Acronym)	Ex (nm)	Em (nm)	EC × 10−3 M−1 cm−1	QY	Relative Brightness (% of EGFP)a	Use as FRET probe	Reference
Aequorea-based FPs
EBFP2	383	448	32.0	0.56	53	Donor to GFP/YFP	9
mCerulean3	433	475	40.0	0.87	103	Donor to YFP	54
mTurquoise	435	477	35.0	0.51	53	Donor to YFP	53
EGFP	488	507	56.0	0.60	100	Donor to OFP, RFP	5
mVenus	515	528	92.2	0.57	156	Acceptor for CFP, Donor to RFP	7
mCitrine	516	529	77.0	0.76	174	Acceptor for CFP	52
T-Sapphire	399	511	44.0	0.60	79	Long Stokes shift donor	56
mAmetrine	406	526	45.0	0.58	78	Long Stokes shift donor	57
REACh	515	528	92.2	0.04	1	Strong absorber, weak emitter Acceptor for FLIM studies	79,80
Coral FPs
Midoriishi Cyan	472	495	27.3	0.90	73	Donor to mKO	15
mTFP1	462	492	64.0	0.85	162	Donor to YFP, OFP, RFP	58
Kusabira Orange2	551	565	63.8	0.62	118	Acceptor for CFP	73
mCherry	587	610	72.0	0.22	47	Acceptor for GFP	67
TagRFP-T	555	584	81.0	0.41	99	Acceptor for GFP	72
mRuby	558	605	112.0	0.35	117	Acceptor for GFP	78

^aEC × QY/EGFP